Device for dusting metallic sheets



Feb. 27, 1934. R. a. DIMMICK 1,949,270

DEVICE FOR DUSTING METALLIC SHEETS Filed April 20, 1931 2 Sheets-Sheet 1 INVENTOR,

elba MM A TTORNEYS Feb. 27, 1934. R. a. DIMMICK 1,949,270

DEVICE FOR DUSTING METALLIC SHEETS I Filed April 20, 1931 2 Sheets-Sheet 2 ATTORNEY Patented Feb. 27, 1934 UNITED STATES PATENT OFFICE 1,949,270 DEVICE FOR DUSTING METALLIC SHEETS Application April 20, 1931. Serial No. 531,416

5 Claims.

My invention relates primarily to means for producing upon the surface of metallic sheets a coating of substance which will act as an effective separator during an annealing or other treatment; and while my invention is susceptible of other uses, it will be described in its exemplary embodiment in connection with the dusting of iron or steel sheets prior to a box-annealing treatment. It has been understood that the sticking of sheets or other metallic shapes could be prevented by the use of powdered substances of a wide variety of kinds. Among these, the most common are graphite and lime. A fundamental object of my invention, of course, is the provislon of means for producing an adequate coating of powdered materials upon the surfaces of metallic sheets.

Particularly in high finished sheets, the use of powdered substances to prevent sticking involves a considerable number of difiiculties. In order that these may be fully understood, I describe as follows an exemplary process of manufacturing automobile sheets. An ingot is first reduced in ;a blooming or slabbilng mill, the bars or slabs of the required size, and these are then hot-rolled to a gauge such that the resultant sheets or strips may be reduced to final gauge by cold-rolling operations. The pieces are pickled and are then :cold-rolled, usually with a reduction of thirty to sixty per cent. After this step in the process, the sheets are white and have a highly polished surface. An annealing follows the cold-rolling opera- :tion, and it is prior to this annealing that the powdered substance or dust is applied to the sheets. After the dusting, the sheets are usually box-annealed, and they are normally given a certain amount of final cold-rolling, at least for surface finish, and to kill their dead soft condition,

after the box annealing.

If the coating of dust applied to the sheets before box-annealing is too thin or is incomplete, purpose will be defeated. If it is too heavy or not uniformly distributed, the pressure developed the box-annealing forces the coating into the After the sheets are shipped, the consumer usually submits them to stamping or drawing operations, and if any of the substance used for the preventation of stick-.ng remains on the sheets, it interferes with the operation of the dies to and causes surface defects. The stampings are very frequently finished with a lacquer, Japan enamel, nickel or chromium plating. Clearly, any appreciable quantity of foreign substance on the sheets interferes with these operations and the results produced thereby.

It is therefore essential that any substance which is used to prevent sticking in box-annealing should be so uniformly distributed and applied so lightly that it will not injure the surface of the sheets in subsequent operations, and will not interfere with any of the processing or finishing operations which may be subsequently performed thereon. Yet it is essential that the coating be adequate and continuous if sticking is to be prevented in the box-annealing.

A number of provisions have been made of ways for applying powdered substances, but these have usually involved considerable inconvenience and expense, and have been characterized by uncer- 8o tainty of results.

The underlying objects of my invention may be summed up in the statement that it is my purpose to provide an adequate means and method of producing a coating of non-sticking substance 35 upon the sheets; and other objects of my invention will be apparent to one skilled in the art upon reading these specifications, or will be pointed out hereinafter. Reference is now made to the accompanying drawings wherein:

Figure 1 is a plan view of an exemplary form of my apparatus.

Figure 2 is an elevation thereof.

Figure 3 is a sectional view along the lines 11 in Figure 2.

Figure 4 is a sectional view along the lines 2--2 in Figure 2.

Figure 5 is a sectional view along the lines 3'3 in Figure 1.

As a dusting substance, I prefer the use of talc, which has hitherto not been employed for. the purpose, so far as I am aware. This substance is particularly adapted for use in my process and device, which, however, are not restricted thereto.

Broadly in the practice of my invention I provide, in connection with suitable conveying means, a box or housing in which the primary application of powdered substance is effected; and I provide within this housing means, hereinafter to be described, insuring an adequate application of the substance to the sheets. I also provide means for removing any excess therefrom. The manner of application which I prefer comprises subjecting the sheets to a cloud or fog of powder particles, i. e., to an atmosphere having particles mechanically suspended therein.

In Figure 1 I have shown a dusting machine comprising a feed table 4 which may, if desired, be in the form of a conveyor, but which, in the embodiment shown, comprises a plurality of rails upon which the sheets may be conveniently handled. This table facilitates the positioning of sheets to be engaged by feed-in pinch rolls 5, whereby the sheets are positively carried forward into the dusting machine proper, indicated by the numeral 6. In Figure 3 the pinch rolls 5 are shown driven through a chain drive or the like 7 by means of a motor 8 which may be fitted with suitable speed reducing or controlling mechanism. I arrange my sheets to be carried through the dusting box upon a suitable conveyor comprising ropes, cables, or belts 9. It is convenient to make the lower of the pinch rolls 5 a portion of this conveying mechanism by grooving it to receive the cables 9, as is shown at 10 in Figure 5. Beyond the dusting box 6 there is a run-out table 11 over which the said cables pass to a series of tail pulleys 12. The cables return beneath this table, and there may be provided an idler roll 13 or series of pulleys at that point in their path of travel where they re-enter the dusting box. They may also be provided with tensioning means comprising pulleys or a. roll 14, and spring or weight means which do not need special description.

The table 11 may be provided at its end with ball bearing rollers 15 to facilitate the stacking of the sheets after they have been treated.

The dusting box comprises a body, indicated at 16, having a lid 17 which may be removed for filling or inspection. The body has a depending body portion in the shape of a V with slanting side members 18 and 19 so shaped that the cross section of the box may be referred to as substantially triangular. The walls 18 and 19 extend longitudinally of the box, and are closed by end pieces 20 and 21, as clearly shown in Figure 5. One of the end pieces may have an inspection or clean-out opening closed by a removable cover member 22, if desired. The bottom of the V may be provided with a longitudinally extending rounded member 24, the purpose of which is to prevent powdered materials from getting down into the point of the V, where they would be substantially inaccessible to the mechanism hereinafter described.

The member 24 may be of sheet metal, and its rounded shape is such as to permit the movement of vanes attached to a shaft 25 which passes through the dusting box and is journaled in suitable bearings 26 and 27 at either end. This shaft is in the form of a hollow pipe, and is perforated at intervals, as at 28, for the escape of air blown into it. It is also fitted with supporting members 29 which hold vanes 30 in positions interspaced from the shaft, so that a collection of dusting material in the bottom of the dusting box may not only be agitated by air blown through the holes 28, but also may be mechanically stirred and agitated by the vanes 01' paddles 30 as the shaft rotates. The shaft is connected by a suitable fluid-tight gland or other means 31, at one of its ends, to a conduit leading to a blower 32 having a motor 33, or to some other source of air. Where a blower is used, a convenient means of regulating the amount of air introduced into the dusting box is shown in Figure 5, where a T 34 is connected into the line between the blower and the shaft, and is also connected, through appropriate intermediate fittings, to a valve 35 open to the air. The valve has a stem 36 to which a rod 37 may be attached for operation, and in the embodiment shown, this rod is hooked so that it may be engaged selectively in a plurality of holes 39 in a plate 38 attached to the frame of the machine. As the valve 35 is opened, the pressure of the air passing into the shaft 25 is cut down, as will be clear.

The other end of the shaft is fitted with a sprocket 40 for driving it through a suitable change speed mechanism 41 by means of a motor 42 or other source of power.

It will be understood that a body of suitable dusting powder 43 placed in the hopper bottom of my device will be mechanically agitated by the blades 30 and blown about by air from the ports 28 to the extent of producing a cloud or atmosphere surcharged with particles of the powder inside the body of my device. In order that as little of this cloud of dust particles as possible may come out of my device into the open air, the openings through which the sheets are introduced therein are made as small as practicable, and one or both of the openings may be provided with a suitable seal 44 which may comprise a flexible material bearing against the sheet and the conveyor ropes 9. So that a pressure will not be built up in my device, I may cover the top frame member 17 with a fabric 45 of such character as to permit the passage of air, but not the passage of the dust particles therein. Inside my housing 16 I may provide supplementary rails 46 to support the sheets if the conveyor sags, and such guide members (not shown) as may be necessary to insure the carrying of the sheets through the dusting box. Inasmuch as I am ordinarily treating sheets which are otherwise ready for a box-annealing step, I am not much troubled with lack of flatness or the like, and the guide members, if any are employed, may be relatively simple.

As the sheet is conveyed through my dusting box, there is deposited upon both surfaces thereof a uniform coating of the dusting material. There is very little tendency toward excessively coated spots or areas, because the powder is deposited upon the surface of the sheet out of a cloud or suspension; yet the coverage is thorough. Under some conditions there may be a tendency for a slightly heavier coating on the top of the sheet where gravity is not effective in causing the coating to fall away. Any excess coating will usually be wiped away, as by felt or other material, lying against the coated sheet in the sealing member 44. I found it advantageous under some circumstances, however, to treat at least the top surface of the sheet with a blast of air after it leaves the dusting box, and to this end I have shown, in the several figures, a conduit 47 extending transversely across the conveyor and fed with air under some pressure by a fan 48 having a motor 49. This conduit is fitted with a suitable series of nozzles 50, whereby blasts of air are directed across the sheet. A suitable valve 51 may be provided to regulate the intensity of the blast delivered by the fan 48 through the conduit 47.

In practice, a dense cloud of dust particles in suspension in the atmosphere within the dusting box coats both the top and bottom surfaces of a sheet passing therethrough on the conveyor 9. The intensity of the application may be regulated by means of the air blast furnished through conduit 25 by the fan 32, and also by the speed with which the motor 42 drives the shaft 25 and the speed by which the motor 8 drives the conveyor 9 and carries the sheets through the machine. The air blast from the conduit 47 removes any concentration of powder in one spot which may fortuitously be left on the upper surface of the sheet. It is not ordinarily necessary or desirable to locate another conduit below the sheet and blow air on its under surface as it leaves the box. However, this may be done if conditions appear to warrant it.

By my machine I secure a uniform, complete, but relatively very fine coating of powdered material on the surface of my sheets, which coating is so impalpable as not to interfere with subsequent operations upon the sheets, yet, by reason of its fineness, is not readily removed therefrom and forms an adequate non-sticking and protective coating during annealing operations. This is done in such a way as to prevent an accumulation of powdered material in the atmosphere of the plant or work room in which my device is located, which atmosphere might be injurious to health, and yet the dusting is done much more efficiently and the coating secured much more complete and uniform than is possible in any hand dusting method, or in any method in which a powdered material is sifted onto the surfaces of sheets.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:--

1. In a dusting machine for metallic sheets, the combination of a closed chamber, means for conveying sheets thereto, means for maintaining in said chamber a body of dusting material out of contact with said sheets, a hollow shaft passing through said chamber in contact with said body of material, means for rotating said shaft, mechanical agitating means non-rotatably fixed to said shaft, perforations in said shaft, and means for supplying fluid under pressure to said shaft.

2. In a dusting machine for metallic sheets, the combination of a closed chamber, means for conveying sheets thereto, means for maintaining in said chamber a body of dusting material out of contact with said sheets, a hollow shaft passing through said chamber in contact with said body of material, means for rotating said shaft, mechanical agitating means non-rotatably fixed to said shaft, perforations in said shaft, means for supplying fluid under pressure to said shaft, and means for directing a fluid blast upon said sheets after removal from said chamber.

3. In a dusting machine for metallic sheets, the combination of a closed chamber, means for conveying sheets thereto, means for maintaining in said chamber a body of dusting material out of contact with said sheets, a hollow shaft passing through said chamber in contact with said body of material, means for rotating said shaft, mechanical agitating means non-rotatably fixed to said shaft, perforations in said shaft, means for supplying fluid under pressure to said shaft, and means for relieving fluid pressure in said chamber while substantially retaining said dusting material therein.

4. In a dusting machine for metallic sheets, the combination of a closed chamber, means for con veying sheets thereto, means for maintaining in said chamber a body of dusting material out of contact with said sheets, a hollow shaft passing through said chamber in contcat with said body of material, means for rotating said shaft, mechanical agitating means non-rotatably fixed to said shaft, perforations in said shaft, means for supplying fluid under pressure to said shaft, means for relieving fluid pressure in said chamber while substantially retaining said dusting material therein, and wiping means arranged to contact said sheets as they leave said chamber.

5. In a dusting machine for metallic sheets, the combination of a closed chamber, means for conveying sheets thereto, means for maintaining in said chamber a body of dusting material out of contact with said sheets, a hollow shaft passing through said chamber in contact with said body of material, means for rotating said shaft, mechanical agitating means non-rotatably fixed to said shaft, perforations in said shaft, means for supplying fluid under pressure to said shaft, means for relieving fluid pressure in said chamber while substantially retaining said dusting material therein, wiping means arranged to contact said sheets as they leave said chamber, and means for directing a fluid blast against said sheets after they leave said chamber.

RALPH B. DIMMICK. 

